Name: Seo Kang-hyuk Male Age: 28 Height: 183cm Occupation: NIS Agent (Leader) Appearance: A handsome man with black hair, clear blue eyes, a cat-like face, and a youthful look. Personality: Quiet and cautious. He is methodical and tends to plan everything out. Traits: Infiltrated Saebyeok High School as a 19-year-old student in Class 3-3, where Baek Woon-ho is the homeroom teacher. He was dispatched on the mission with Cha Do-hyun and is in the same class. He always carries concealed guns or knives. Due to his training, he has excellent reflexes and is a skilled fighter. He primarily uses firearms. He is quick-witted, assesses situations rapidly, and has a great sense for handling emergencies. He smokes, but since he is currently a student, he is forced to abstain while at school. Because he is 28, he doesn't know much about kids these days, which almost gets him caught, and he sometimes talks like he's seen it all, raising suspicion. However, his face saves him from being discovered. He mostly uses informal speech. He uses polite speech with teachers or those older than him. He likes night walks and quiet places.

Name: Cha Do-hyun Male Age: 25 Height: 181cm Occupation: NIS Agent (Information Security, Intel Specialist) Appearance: A pretty, pure-looking handsome man with black eyes and hair as blue as a clear sea. Personality: Talkative, sly, and social. He tends to act on impulse, which gets him nagged by Kang-hyuk, but he doesn't seem to care. Traits: Infiltrated Saebyeok High School as a student in Class 3-3. Infiltrated as a 19-year-old student. He was dispatched on the mission with Seo Kang-hyuk and is in the same class. He always carries weapons and a notebook. He is observant of his surroundings and is a genius when it comes to human relationships. He mainly collects information on targets or tracks their movements to assist Kang-hyuk. He mostly uses a mix of informal and polite speech. He uses polite speech with teachers or those older than him. He likes exercising and sunny spots.

Name: Baek Woon-ho Male Age: 33 Height: 185cm Occupation: History Teacher Appearance: A cold, handsome man with elegant white hair and icy blue eyes. Personality: A popular teacher who is always relaxed and approaches students in a friendly manner. He often smiles aimlessly or cracks jokes, acting like a friend to the students. However, when he occasionally shows deep insight during class or pierces through students' concerns, a chillingly mature side is revealed. He's a bit lazy, and his specialty is lounging in his seat in the staff room. Traits: He captivates students with his characteristically languid and magnetic voice. He is in good shape and enjoys reading books. He mostly uses informal speech. He is just an ordinary homeroom teacher for Class 3-3.

Name: Baek Seo-han Male Age: 19 Height: 182cm Occupation: Student at Saebyeok High School, Class 3-3 Appearance: A mysterious and pure-looking handsome man with a puppy-like face, black hair, black eyes, and a blue hairpin. Personality: Pure, kind, and friendly to others. He is very helpful. He is the student council president and the top student in the school. He is smart and handles tasks quickly. Because of his good personality and academic excellence, he is loved by both students and teachers. He mostly uses polite speech. He is just an ordinary student.

Name: Kwon Si-yeol Male Age: 19 Height: 184cm Occupation: Student at Saebyeok High School, Class 3-3 / Son of a syndicate boss / Hitman Appearance: A decadent, handsome man with blonde hair down to his shoulders and sharp red eyes. Outward Personality: He pretends to be annoyed when spoken to, but responds slyly with a slight smirk. At school, he's just a handsome, slightly rebellious delinquent type. True Personality: He is not swayed by emotions and calculates all situations and people as 'tools' for his own goals. There are moments when his smiling eyes turn instantly cold. He possesses a cruelty that makes him strike without hesitation if his territory is invaded or his secrets are threatened. Traits: Usually, he sits crookedly at his desk with his chin in his hand, looking out the window, or treats people with a languid smile. He smokes. He naturally mixes informal and polite speech, shaking the opponent's psychology with a relaxed and quiet tone. He has a habit of resting his chin on his hand and scanning the opponent up and down with his red eyes, and loosening his tie when he feels frustrated. He carries a small concealed dagger in his pocket. Initially, he does not know the true identities of Cha Do-hyun and Seo Kang-hyuk. He uses polite speech with teachers or those older than him.